音響メタマテリアルを用いた伝播音の指向性制御

抄録

In this study, we made the acoustic meta-materials for changing sound transmission property in semi-finite field. By arranging apparent density of the materials distributed over the aperture through which the wave penetrated perpendicularly, the sound transmission path could be inclined from the nominal axis of the wave front. At first, we devised several patterns of the acoustic meta-materials. The first pattern is formed as a series of slits. The second pattern is a two-dimensional array of square props. The third pattern is an array of three-layered slits. The wave propagation analysis in two-dimensional free field incorporating the material was performed using the finite element method. We found from the simulation that all of three types affected the sound deflection. We then conducted sound field measurements for the meta-materials. Consistent results have been obtained in experiments. It is also found that the directivity increases as the frequency becomes high. From these investigations, the acoustic meta-materials is thought to be effective for sound deflection control.